Seven cases of PLB in females were reviewed. Six cases involved the breast alone (stage 1E), whereas one case also involved the ipsilateral lymph nodes (stage 2E). None had B symptoms. The age range was 37-70 years (mean 52 years). The clinical course was indistinguishable from that of breast carcinomas, though the tumors were relatively large and the duration of symptoms was relatively short. Histologically, all cases were non-Hodgkin's B-cell lymphomas, comprising five cases of diffuse centroblastic type, one case of diffuse centroblastic-centrocytoid type and one case of follicular centroblastic-centrocytic type, according to the updated Kiel classification, corresponding to six cases of the diffuse large cell type and one case of the follicular mixed, small cleaved and large cell type, according to the modified International Working Formulation (IWF). None of the cases was a lymphoma of mucosa-associated lymphoid tissue (MALT). The mammary glandular tissue outside the tumor showed ductectasia in four cases. Changes resembling fibrous disease of the breast were seen in four cases, too. The inflammatory infiltration in all these cases was mainly composed of T cells. At the time of diagnosis, all patients were receiving cytoreductive treatment. The mean follow-up time was 34 months (range 5-79 months). At present, six of the patients are alive and well.